Rauglothgor's Lair is an excellent realm to add to your deck. Unless you are up against a dragon deck, most opponents will start at half their base level. This alone makes it worthwhile. Once you add in the fact that defending undead are immune to harmful events, it becomes a must to any undead theme deck.

Be aware that only the undead defenders are immune to the events, not the realm itself, so although Nemon Hotep [NS-67] would be immune to the effects of any harmful events while defending this realm, Rauglothgor's Lair could still be affected by Cataclysm! [4th-119]. One of the best ways to make the most out of Rauglothgor's Lair is to put it in the front rank of your realms and put down the rule card Negative Planar Energy [NS-83].

Now, not only are nondragons at half base level, your undead defenders can first subtract their base level from the attacker's base level. If reduced to 0 or less, they are discarded, and the spoils is yours. You can make this even more deadly by having Powers of the Land [DR-12] attached to another realm in your formation, (Powers of the Land is a Ravenloft holding, so it cannot be attached to Rauglothgor's Lair) and have all of your defending undead double their base levels.